Android Canvas 两种使用方式

From:http://blog.csdn.net/androiddevelop/article/details/8267312

一、Canvas第一种使用方式

最简单的使用Canvas， 画一个方形，一行字。 下面是效果图

public class CustomView extends View {

    private Paint mPaint;

    public CustomView(Context context) {
    super(context);
    }

    public CustomView(Context context, AttributeSet attrs) {
    super(context, attrs);

        mPaint = new Paint();
        mPaint.setColor(Color.GREEN);
        mPaint.setTextSize(36);

    }

    @Override
    protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

        mPaint.setStyle(Style.FILL); //设置填充
        canvas.drawRect(10, 10, 200, 200, mPaint); //绘制矩形

        mPaint.setColor(Color.BLUE);
        canvas.drawText("我不是自定义View", 10, 120, mPaint);
    }

public class CustomView extends View {

    private Paint mPaint;
    
    public CustomView(Context context) {
	super(context);
    }
    
    public CustomView(Context context, AttributeSet attrs) {
	super(context, attrs);
	
	    mPaint = new Paint();  
        mPaint.setColor(Color.GREEN);  
        mPaint.setTextSize(36);  
          
    }

    @Override
    protected void onDraw(Canvas canvas) {
	super.onDraw(canvas);

	    mPaint.setStyle(Style.FILL); //设置填充  
        canvas.drawRect(10, 10, 200, 200, mPaint); //绘制矩形  
          
        mPaint.setColor(Color.BLUE);  
        canvas.drawText("我不是自定义View", 10, 120, mPaint);  
    }

参考资料：

android图形系统详解一：Canvas

android Canvas类介绍

Android Graphic ： apk and Skia/OpenGL|ES

二、Canvas第二种使用方式

Canvas的使用通常只有两种形式：

1.  在已有的Canvas上绘制图形或文字，通过VIew.onDraw回调获取Canvas对象。Canvas第一种使用方式

2.  图形或文字直接绘制到View上（本文使用此种方式）

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Bitmap b =Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);
        Canvas canvas =new Canvas(b);

        Paint paint = new Paint();
        paint.setColor(Color.BLUE);
        canvas.drawText("love_world_", 20, 20, paint);

        ImageView imageView = (ImageView) findViewById(R.id.image_view);
        BitmapDrawable bitmapDrawable = new BitmapDrawable(b);
        imageView.setBackgroundDrawable(bitmapDrawable);
    }

}

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		Bitmap b =Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);
		Canvas canvas =new Canvas(b);
		
		Paint paint = new Paint();
		paint.setColor(Color.BLUE);
		canvas.drawText("love_world_", 20, 20, paint);
		
		ImageView imageView = (ImageView) findViewById(R.id.image_view);
		BitmapDrawable bitmapDrawable = new BitmapDrawable(b);
		imageView.setBackgroundDrawable(bitmapDrawable);
	}

}

效果图

Android入门第十四篇之画图

http://blog.csdn.net/hellogv/article/category/761980

Andriod中绘(画)图----Canvas的使用详解

http://blog.csdn.net/qinjuning/article/details/6936783

Android图像处理之Bitmap类
http://blog.csdn.net/thl789/article/details/6762030

Android利用canvas画各种图形(点、直线、弧、圆、椭圆、文字、矩形、多边形、曲线、圆角矩形)

http://blog.csdn.net/rhljiayou/article/details/7212620

画了个Android——Canvas类的使用

http://blog.sina.com.cn/s/blog_61ef49250100qw9x.html

Android Canvas rotate

http://verydemo.com/demo_c131_i3507.html

Android入门第十四篇之画图

http://blog.csdn.net/hellogv/article/category/761980

Andriod中绘(画)图----Canvas的使用详解

http://blog.csdn.net/qinjuning/article/details/6936783

Android图像处理之Bitmap类
http://blog.csdn.net/thl789/article/details/6762030

Android利用canvas画各种图形(点、直线、弧、圆、椭圆、文字、矩形、多边形、曲线、圆角矩形)

http://blog.csdn.net/rhljiayou/article/details/7212620

画了个Android——Canvas类的使用

http://blog.sina.com.cn/s/blog_61ef49250100qw9x.html

Android Canvas rotate

http://verydemo.com/demo_c131_i3507.html